肋片几何形状对仿螺旋肋片内冷通道流动与换热的影响

利用数值模拟方法,分析了仿螺旋肋片内冷通道在通道宽高比AR=2.9、肋高与通道当量直径比e/Dh=0.336、肋高与通道高度比e/H=0.5、肋片与轴面的夹角β=15°及雷诺数在1×104 to 2×105之间时,矩形肋片和楔形肋片对仿螺旋肋片内冷通道强化传热与流动阻力特性的影响。计算结果表明,仿螺旋内冷通道平均换热系数得到了明显的提高,但同时流动阻力也显著增加。在所研究的范围内,矩形仿螺旋肋片内冷通道的换热强化比要高于同等几何排列条件下的楔形仿螺旋肋片内冷通道,但其综合肋化效率要低于相同几何排列条件下的楔形仿螺旋肋片内冷通道。 

Effect of Helix-Alike Fin Surface Shape on Flow and Heat Transfer in the Internal Cooling Passage

3-D Navier-Stokes equations were solved with the conventional k-ε turbulence model to predict turbulent flow and heat transfer in the internal cooling passage of the gas turbine blades,in which the staggered arrays of discrete helix-alike rectangular-fins or wedged-fins with a certain angle were used along two inside opposite walls.Results were presented for Reynolds number in the range of 1×104 to 2×105,cross-section aspect ratio of 2.9,fin height to hydraulic diameter ratio of 0.336,fin height to passage height ratio of 0.5,and the inclined angle of the helixalike fin of 15°.A complicated 3-D accelerated spiral-flow which just likes the fluid flow in helical-fin tube has been formed and it has significant effects on the heat transfer.The averaged Nusselt number ratios decrease and the friction factor ratios increase with the increasing Reynolds number for all the studied cases.Also the detailed discussion of the influence of helix-alike fin surface shape on heat transfer and pressure drop was given.It is found that,the heat transfer enhancement in the internal cooling passage with helix-alike rectangular-fin is better than others,but the comprehensive enhancement performance ratio is lower than that with helix-alike wedged fins.